Deviation of the Fecal Stream in Colonic Bowel Segments Results in Increased Numbers of Isolated Lymphoid Follicles in the Submucosal Compartment in a Novel Murine Model of Diversion Colitis

Figure 7

Lymphoid follicles and inflammatory infiltrate. (a) Lymphoid follicles of the diverted colon and sham animals were counted on paraffin sections stained with hematoxylin and eosin. The graph shows the mean and standard error of 5 to 9 animals per group (DC 14 and 30 days, sham 14 days: ; DC 60 days: ; sham 30 and 60 days: ). (b) and (c) Representative examples of sections made of the rectum of DC (b) and sham (c) animals 60 days postoperatively stained with hematoxylin and eosin. A prominent lymphoid follicle () is present in the mucosa of the DC mouse. Scale bars represent 100 μm. (d) and (e) HE-stained sections of the rectum showed a slight hypercellularity () due to inflammatory mononuclear cells in the lamina propria of DC animals (d) compared to the sham group (e). Scale bars represent 50 μm. (f), (g), and (h) Staining with chloroacetate esterase reaction was performed to detect neutrophil granulocytes. A representative section of the vicinity of the colostomy opening illustrates an influx of neutrophils (Δ) 60 days postoperatively (f). On cross sections of the diverted rectum, an acute inflammatory neutrophilic infiltrate was observed neither in the DC group (g) nor in sham animals (h) up to 60 days postoperatively. Scale bars represent 100 μm. (i) Human diversion colitis is characterized by a mild chronic inflammatory hypercellularity () and edema of the lamina propria, slightly irregular crypts (#), and an increased number of enlarged lymphoid follicles (). No epithelial erosions were observed. Scale bars represent 100 μm.

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